Typical caps, such as baseball caps, are not well adapted for cold weather use. In fact, these caps are designed to provide air flow over the head to increase cooling. Many other types of headgear not specifically designed for cold weather are also ill suited for heat retention.
Prior art devices have sought to provide insulation for caps and hats to improve the comfort and heat retention of the headgear. One such device is disclosed in U.S. Pat. No. 4,949,404 issued to Fekete, Sr. on Aug. 21, 1990. The device comprises an insulating member including stretchable woven tubes which fit tightly about the user's head. However, the device is not well suited for a cap or similar headgear because it can not be removably retained by a cap and is too thick to comfortably fit between the cap and the user's head.